I have a 1999 Mazda Protege 1.6L with 191000 miles on it. The computer analyzer wont read the computer. My check engine light came on so I went to get it checked. They said it wasn't working so I went to my Grandpas to try cause he has a computer analyzer also. i plugged it in and turned on the ignition and it didn't do anything. It still said plug into car hookup. My sister has the same exact car. Same year, model, engine size, color, everything and i tried it in he car today and it worked fine. What's wrong?